U.S. patent number 7,328,638 [Application Number 11/318,707] was granted by the patent office on 2008-02-12 for cutting tool using interrupted cut fast tool servo.
This patent grant is currently assigned to 3M Innovative Properties Company. Invention is credited to Alan B. Campbell, Dale L. Ehnes, Mark E. Gardiner, Daniel S. Wertz.
United States Patent |
7,328,638 |
Gardiner , et al. |
February 12, 2008 |
**Please see images for:
( Certificate of Correction ) ** |
Cutting tool using interrupted cut fast tool servo
Abstract
A cutting tool assembly having a tool post capable of lateral
movement along a work piece to be cut and an actuator with a tool
tip. The actuator provides for control of the movement of the tool
tip in an x-direction into and out of the work piece in order to
make discontinuous microstructures in it. The machined work piece
can be used to make microstructured articles such as films having
non-adjacent lenslets.
Inventors: |
Gardiner; Mark E. (Santa Rosa,
CA), Campbell; Alan B. (Santa Rosa, CA), Ehnes; Dale
L. (Cotati, CA), Wertz; Daniel S. (Sebastopol, CA) |
Assignee: |
3M Innovative Properties
Company (St. Paul, MN)
|
Family
ID: |
38192077 |
Appl.
No.: |
11/318,707 |
Filed: |
December 27, 2005 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20070144315 A1 |
Jun 28, 2007 |
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Current U.S.
Class: |
82/123; 82/157;
82/70.1 |
Current CPC
Class: |
B23B
27/20 (20130101); B23B 29/125 (20130101); B23Q
15/14 (20130101); B23B 2260/108 (20130101); G05B
2219/41344 (20130101); Y10T 82/2583 (20150115); Y10T
82/2512 (20150115); Y10T 82/10 (20150115); Y10T
82/16426 (20150115) |
Current International
Class: |
B23B
3/00 (20060101) |
Field of
Search: |
;82/1.11,70.1,123,157,117,158 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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63-077643 |
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Apr 1988 |
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JP |
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9-275689 |
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Oct 1997 |
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JP |
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2002-301601 |
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Oct 2002 |
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JP |
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2004098230 |
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Apr 2004 |
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JP |
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2004096676 |
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Sep 2005 |
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KR |
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WO 97/48521 |
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Dec 1997 |
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WO |
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WO 00/25963 |
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May 2000 |
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WO |
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WO 00/50201 |
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Aug 2000 |
|
WO |
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WO 02/06005 |
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Jan 2002 |
|
WO |
|
WO 02/37168 |
|
May 2002 |
|
WO |
|
WO 02/37168 |
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May 2002 |
|
WO |
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WO 03/086688 |
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Oct 2003 |
|
WO |
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WO 2005/043266 |
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May 2005 |
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WO |
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WO 2005/043266 |
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May 2005 |
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WO |
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Other References
UltraMill Research@PEC,NCSU, "Vibration Assisted Machining:
Ultramill," North Carolina State University Precision Engineering
Center, Raleigh, NC 27695,
[http://airy.pec.ncsu.edu/PEC/research/projects/ultramill/index.ht-
ml], Spring 2000, pp. 2. cited by other .
Edward M. Trent & Paul K. Wright, Metal Cutting, 4th ed.,
Butterworth, Heinemann, 2000, pp. 258-260. cited by other .
Zhang Jin-Hua, Theory and Technique of Precision Cutting, Pergamon
Press, 1991, Chap. 2, "Nature of Cutting Force Variation in
Precision Cutting," pp. 18-31. cited by other .
M. K. Krueger, S. C. Yoon, D. Gong, S. B. McSpadden Jr., L. J.
O'Rourke, R. J. Parten, "New Technology in Metalworking Fluids and
Grinding Wheels Achieves Tenfold Improvement in Grinding
Performance," Coolants/Lubricants for Metal Cutting and Grinding
Conference, Chicago, Illinois, Milacron, Inc. and Oak Ridge
National Laboratory, Jun. 7, 2000, pp. 15. cited by other.
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Primary Examiner: Fridie, Jr.; Willmon
Attorney, Agent or Firm: Vietzke; Lance L.
Claims
What is claimed is:
1. An apparatus for machining a cylindrical work piece, comprising:
a substantially cylindrical work piece mounted for rotational
movement; a drive unit connected to the work piece for rotating the
work piece; a tool post mounted on a track for movement
substantially parallel to a surface of the work piece to be
machined; an actuator mounted on the tool post, the actuator
comprising: a main body having an aperture; a piezoelectric stack
secured and preloaded in the main body aperture; a tool tip carrier
connected to the piezoelectric stack; and a tool tip mounted on the
tool tip carrier, wherein the piezoeloctric stack moves the tool
tip in an x-direction substantially perpendicular to a surface of
the work piece to be machined; and a controller, connected to the
drive unit and the actuator, for controlling the movement of the
work piece relative to the tool tip via the drive unit and for
controlling the movement of the tool tip via the piezoelectric
stack, wherein the controller via the piezoelectric stack moves the
tool tip into and out of the surface of the work piece to be
machined during cutting of the surface in order to make
discontinuous features in the surface of the work piece.
2. The apparatus of claim 1, wherein the actuator is removably
mounted to the tool post.
3. The apparatus of claim 1, further including a plate attached
between the piezoelectric stack and the tool tip for the preloading
of the piezoelectric stack.
4. The apparatus of claim 1, wherein the piezoelectric stack is
comprised of one of the following materials: barium titanate; lead
zirconate; lead titanate; or a magnetostrictive material.
5. The apparatus of claim 1, wherein the main body includes an
aperture having a port for receiving a cooling fluid.
6. The apparatus of claim 4, wherein the plate comprises a
Belleville washer.
7. The apparatus of claim 1, wherein the main body is comprised of
stainless steel.
8. The apparatus of claim 5, further comprising a cooling fluid
reservoir connected to the port for delivering the cooling fluid to
the aperture.
9. The apparatus of claim 1, wherein the controller causes movement
of the tool tip into and out of the surface of the work piece to be
machined such that a taper-in angle of the tool tip into the
surface of the work piece is substantially equal to a taper-out
angle of the tool tip out of the surface of the work piece during
the machining.
10. The apparatus of claim 1, wherein the controller causes
movement of the tool tip into and out of the surface of the work
piece to be machined such that a taper-in angle of the tool tip
into the surface of the work piece is less than a taperout angle of
the tool tip out of the surface of the work piece during the
machining.
11. The apparatus of claim 1, wherein the controller causes
movement of the tool tip into and out of the surface of the work
piece to be machined such that a taper-in angle of the tool tip
into the surface of the work piece is greater than a taper-out
angle of the tool tip out of the surface of the work piece during
the machining.
12. The apparatus of claim 1, wherein the features cut by the tool
tip have one of the following shapes: symmetrical; asymmetrical;
semi-bemispherical; prismatic; or semi-ellipsoidal.
13. The apparatus of claim 1, wherein the features cut by the tool
tip have a pitch between 1 and 1000 microns.
14. The apparatus of claim 1, wherein the tool tip carrier is
comprised of one of the following materials: sintered carbide;
silicon nitride; silicon, carbide; steel; titanium; diamond; or
synthetic diamond material.
15. The apparatus of claim 1, wherein the tool tip carrier has a
planar back surface connected to the piezoelectric stack.
16. The apparatus of claim 15, wherein the tool tip carrier has a
tapered front surface opposite the back surface.
Description
BACKGROUND
Machining techniques can be used to create a wide variety of work
pieces such as microreplication tools. Microreplication tools are
commonly used for extrusion processes, injection molding processes,
embossing processes, casting processes, or the like, to create
microreplicated structures. The microreplicated structures may
comprise optical films, abrasive films, adhesive films, mechanical
fasteners having self-mating profiles, or any molded or extruded
parts having microreplicated features of relatively small
dimensions, such as dimensions less than approximately 1000
microns.
The microstructures can also be made by various other methods. For
example, the structure of the master tool can be transferred on
other media, such as to a belt or web of polymeric material, by a
cast and cure process from the master tool to form a production
tool; this production tool is then used to make the microreplicated
structure. Other methods such as electroforming can be used to copy
the master tool. Another alternate method to make a light directing
film is to directly cut or machine a transparent material to form
the appropriate structures. Other techniques include chemical
etching, bead blasting, or other stochastic surface modification
techniques.
SUMMARY
A first cutting tool assembly includes a tool post and an actuator
configured for attachment to the tool post and for electrical
communication with a controller. A tool tip attached to the
actuator is mounted for movement with respect to a work piece to be
cut. The actuator provides for movement of the tool tip in an
x-direction into and out of the work piece, and the tool tip is in
discontinuous contact with the work piece during cutting of it.
A second cutting tool assembly includes a tool post and an actuator
configured for attachment to the tool post and for electrical
communication with a controller. A tool tip attached to the
actuator is mounted for movement with respect to a work piece to be
cut. The actuator provides for movement of the tool tip in an
x-direction into and out of the work piece. The tool tip is in
discontinuous contact with the work piece during cutting, and the
assembly can vary a taper-in angle of the tool tip into the work
piece and a taper-out angle of the tool tip out of the work piece
during the cutting.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings are incorporated in and constitute a part
of this specification and, together with the description, explain
the advantages and principles of the invention. In the
drawings,
FIG. 1 is a diagram of a cutting tool system for making
microstructures in a work piece;
FIG. 2 is a diagram illustrating a coordinate system for a cutting
tool;
FIG. 3 is a diagram of an exemplary PZT stack for use in a cutting
tool;
FIG. 4A is a perspective view of a tool tip carrier;
FIG. 4B is a front view of a tool tip carrier for holding a tool
tip;
FIG. 4C is a side view of a tool tip carrier;
FIG. 4D is a top view of a tool tip carrier;
FIG. 5A is a perspective view of a tool tip;
FIG. 5B is a front view of a tool tip;
FIG. 5C is a bottom view of a tool tip;
FIG. 5D is a side view of a tool tip;
FIG. 6A is a top sectional view of an interrupted cut FTS
actuator;
FIG. 6B is a front sectional view illustrating placement of a PZT
stack in an actuator;
FIG. 6C is a front view of an actuator;
FIG. 6D is a back view of an actuator;
FIG. 6E is a top view of an actuator;
FIGS. 6F and 6G are side views of an actuator;
FIG. 6H is a perspective view of an actuator;
FIG. 7A is a diagram illustrating an interrupted cut with
substantially equal taper-in and taper-out angles into and out of a
work piece;
FIG. 7B is a diagram illustrating an interrupted cut with a
taper-in angle less than a taper-out angle into and out of a work
piece;
FIG. 7C is a diagram illustrating an interrupted cut with a
taper-in angle greater than a taper-out angle into and out of a
work piece; and
FIG. 8 is a diagram conceptually illustrating microstructures that
can be made using the cutting tool system having an interrupted cut
FTS actuator.
DETAILED DESCRIPTION
Cutting Tool System
General diamond turning techniques are described in PCT Published
Application WO 00/48037, incorporated herein by reference as if
fully set forth. The apparatus used in methods and for making
optical films or other films can include a fast servo tool. As
disclosed in WO 00/48037, a fast tool servo (FTS) is a solid state
piezoelectric (PZT) device, referred to as a PZT stack, which
rapidly adjusts the position of a cutting tool attached to the PZT
stack. The FTS allows for highly precise and high speed movement of
the cutting tool in directions within a coordinate system as
further described below.
FIG. 1 is a diagram of a cutting tool system 10 for making
microstructures in a work piece. Microstructures can include any
type, shape, and dimension of structures on, indenting into, or
protruding from the surface of an article. For example,
microstructures created using the actuators and system described in
the present specification can have a 1000 micron pitch, 100 micron
pitch, 1 micron pitch, or even a sub-optical wavelength pitch
around 200 nanometers (nm). Alternatively, in other embodiments,
the pitch for the microstructures can be greater than 1000 microns,
regardless as to how they are cut. These dimensions are provided
for illustrative purposes only, and microstructures made using the
actuators and system described in the present specification can
have any dimension within the range capable of being tooled using
the system.
System 10 is controlled by a computer 12. Computer 12 has, for
example, the following components: a memory 14 storing one or more
applications 16; a secondary storage 18 providing for non-volatile
storage of information; an input device 20 for receiving
information or commands; a processor 22 for executing applications
stored in memory 16 or secondary storage 18, or received from
another source; a display device 24 for outputting a visual display
of information; and an output device 26 for outputting information
in other forms such as speakers for audio information or a printer
for a hardcopy of information.
The cutting of a work piece 54 is performed by a tool tip 44. An
actuator 38 controls movement of tool tip 44 as work piece 54 is
rotated by a drive unit and encoder 56, such as an electric motor
controlled by computer 12. In this example, work piece 54 is shown
in roll form; however, it can be implemented in planar form. Any
machineable materials could be used; for example, the work piece
can be implemented with aluminum, nickel, copper, brass, steel, or
plastics (e.g., acrylics). The particular material to be used may
depend, for example, upon a particular desired application such as
various films made using the machined work piece. Actuator 38, and
the actuators described below, can be implemented with stainless
steel, for example, or other materials.
Actuator 38 is removably connected to a tool post 36, which is in
turn located on a track 32. The tool post 36 and actuator 38 are
configured on track 32 to move in both an x-direction and a
z-direction as shown by arrows 40 and 42. Computer 12 is in
electrical connection with tool post 36 and actuator 38 via one or
more amplifiers 30. When functioning as a controller, computer 12
controls movement of tool post 36 along track 32 and movement of
tool tip 44 via actuator 38 for machining work piece 54. If an
actuator has multiple PZT stacks, it can use separate amplifiers to
independently control each PZT stack for use in independently
controlling movement of a tool tip attached to the stacks. Computer
12 can make use of a function generator 28 in order to provide
waveforms to actuator 38 in order to machine various
microstructures in work piece 54, as further explained below.
The machining of work piece 54 is accomplished by coordinated
movements of various components. In particular, the system, under
control of computer 12, can coordinate and control movement of
actuator 38, via movement of tool post 36, along with movement of
the work piece in the c-direction and movement of tool tip 44 in
one or more of the x-direction, y-direction, and z-direction, those
coordinates being explained below. The system typically moves tool
post 36 at a constant speed in the z-direction, although a varying
speed may be used. The movements of tool post 36 and tool tip 44
are typically synchronized with the movement of work piece 54 in
the c-direction (rotational movement as represented by line 53).
All of these movements can be controlled using, for example,
numerical control techniques or a numerical controller (NC)
implemented in software, firmware, or a combination in computer
12.
The cutting of the work piece can include continuous and
discontinuous cutting motion. For a work piece in roll form, the
cutting can include a helix-type cutting (sometimes referred to as
thread cutting) or individual circles around or about the roll. For
a work piece in planar form, the cutting can include a spiral-type
cutting or individual circles on or about the work piece. An X-cut
can also be used, which involves a nearly straight cutting format
where the diamond tool tip can traverse in and out of the work
piece but the overall motion of the tool post is rectilinear. The
cutting can also include a combination of these types of
motions.
Work piece 54, after having been machined, can be used to make
films having the corresponding microstructures for use in a variety
of applications. Examples of those films include optical films,
friction control films, and micro-fasteners or other mechanical
microstructured components. The films are typically made using a
coating process in which a polymeric material in a viscous state is
applied to the work piece, allowed to at least partially cure, and
then removed. The film composed of the cured polymer material will
have substantially the opposite structures than those in the work
piece. For example, an indentation in the work piece results in a
protrusion in the resulting film. Work piece 54, after having been
machined, can also be used to make other articles having discrete
elements or microstructures corresponding with those in the
tool.
Cooling fluid 46 is used to control the temperature of tool post 36
and actuator 38 via lines 48 and 50. A temperature control unit 52
can maintain a substantially constant temperature of the cooling
fluid as it is circulated through tool post 36 and actuator 38.
Temperature control unit 52 can be implemented with any device for
providing temperature control of a fluid. The cooling fluid can be
implemented with an oil product, for example a low viscosity oil.
The temperature control unit 52 and reservoir for cooling fluid 46
can include pumps to circulate the fluid through tool post 36 and
actuator 38, and they also typically include a refrigeration system
to remove heat from the fluid in order to maintain it at a
substantially constant temperature. Refrigeration and pump systems
to circulate and provide temperature control of a fluid are known
in the art. In certain embodiments, the cooling fluid can also be
applied to work piece 54 in order to maintain a substantially
constant surface temperature of the material to be machined in the
work piece.
FIG. 2 is a diagram illustrating a coordinate system for a cutting
tool such as system 10. The coordinate system is shown as movement
of a tool tip 62 with respect to a work piece 64. Tool tip 62 may
correspond with tool tip 44 and is typically attached to a carrier
60, which is attached to an actuator. The coordinate system, in
this exemplary embodiment, includes an x-direction 66, a
y-direction 68, and a z-direction 70. The x-direction 66 refers to
movement in a direction substantially perpendicular to work piece
64. The y-direction 68 refers to movement in a direction
transversely across work piece 64 such as in a direction
substantially parallel to a plane of rotation of work piece 64. The
z-direction 70 refers to movement in a direction laterally along
work piece 64 such as in a direction substantially parallel to the
axis of rotation of work piece 64. The rotation of the work piece
is referred to as the c-direction, as also shown in FIG. 1. If the
work piece is implemented in planar form, as opposed to roll form,
then the y-direction and z-direction refer to movement in mutually
orthogonal directions across the work piece in directions
substantially perpendicular to the x-direction. A planar form work
piece can include, for example, a rotating disk or any other
configuration of a planar material.
The system 10 can be used for, high precision, high speed
machining. This type of machining must account for a variety of
parameters, such as the coordinated speeds of the components and
the work piece material. It typically must take into consideration
the specific energy for a given volume of metal to be machined, for
example, along with the thermal stability and properties of the
work piece material. Cutting parameters relating to machining are
described in the following references, all of which are
incorporated herein by reference as if fully set forth: Machining
Data Handbook, Library of Congress Catalog Card No. 66-60051,
Second Edition (1972); Edward Trent and Paul Wright, Metal Cutting,
Fourth Edition, Butterworth-Heinemann, ISBN 0-7506-7069-X (2000);
Zhang Jin-Hua, Theory and Technique of Precision Cutting, Pergamon
Press, ISBN 0-08-035891-8(1991); and M. K. Krueger et al., New
Technology in Metalworking Fluids and Grinding Wheels Achieves
Tenfold Improvement in Grinding Performance, Coolant/Lubricants for
Metal Cutting and Grinding Conference, Chicago, Ill., U.S.A., Jun.
7, 2000.
PZT Stack, Tool Tip Carrier, and Tool Tip
FIG. 3 is a diagram of an exemplary PZT stack 72 for use in a
cutting tool. A PZT stack is used to provide movement of a tool tip
connected to it and operates according to the PZT effect, which is
known in the art. According to the PZT effect, an electric field
applied to certain types of materials causes expansion of them
along one axis and contraction along another axis. A PZT stack
typically includes a plurality of materials 74, 76, and 78 enclosed
within a casing 84 and mounted on a base plate 86. The materials in
this exemplary embodiment are implemented with a ceramic material
subject to the PZT effect. Three disks 74, 76, and 78 are shown for
exemplary purposes only and any number of disks or other materials,
and any type of shapes of them, can be used based upon, for
example, requirements of particular embodiments. A post 88 is
adhered to the disks and protrudes from casing 84. The disks can be
implemented with any PZT material such as for example, a barium
titanate, lead zirconate, or lead titanate material mixed, pressed,
based, and sintered. One such PZT material is available from
Kinetic Ceramics, Inc., 26240 Industrial Blvd., Hayward, Calif.
94545, U.S.A. The disks can also be implemented with a
magnetostrictive material, for example.
Electrical connections to the disks 74, 76, and 78, as represented
by lines 80 and 82, provide electrical fields to them in order to
provide for movement of post 88. Due to the PZT effect and based
upon the type of electric field applied, precise and small movement
of post 88, such as movement within several microns, can be
accomplished. Also, the end of PZT stack 72 having post 88 can be
mounted against one or more Belleville washers, which provides for
preloading of the PZT stack. The Belleville washers have some
flexibility to permit movement of post 88 and a tool tip attached
to it.
FIGS. 4A-4D are views of an exemplary tool tip carrier 90, which
would be mounted to post 88 of the PZT stack for control by an
actuator, as explained below. FIG. 4A is a perspective view of tool
tip carrier 90. FIG. 4B is a front view of tool tip carrier 90.
FIG. 4C is a side view of tool tip carrier 90. FIG. 4D is a top
view of tool tip carrier 90.
As shown in FIGS. 4A-4D, tool tip carrier 90 includes a planar back
surface 92, a tapered front surface 94, and a protruding surface 98
with angled or tapered sides. An aperture 96 provides for mounting
of tool tip carrier 90 onto a post of a PZT stack. Tapered surface
98 would be used for mounting of a tool tip for machining of a work
piece. In this exemplary embodiment, tool tip carrier 90 includes a
planar surface to enhance stability of mounting it by providing for
more surface area contact when mounted to a PZT stack, and it
includes the tapered front surfaces to reduce the mass of it. Tool
tip carrier 90 would be mounted to post 88 of the PZT stack by use
of an adhesive, brazing, soldering, a fastener such as a bolt, or
in other ways.
Other configurations of tool tip carriers are possible based, for
example, upon requirements of particular embodiment. The term "tool
tip carrier" is intended to include any type of structure for use
in holding a tool tip for machining a work piece. Tool tip carrier
90 can be implemented with, for example, one or more of the
following materials: sintered carbide, silicon nitride, silicon
carbide, steel, titanium, diamond, or synthetic diamond material.
The material for tool tip carrier 90 preferably is stiff and has a
low mass.
FIGS. 5A-5D are views of an exemplary tool tip 100, which would be
secured to surface 98 of tool tip carrier 90 such as by use of an
adhesive, brazing, soldering, or in other ways. FIG. 5A is a
perspective view of tool tip 100. FIG. 5B is a front view of tool
tip 100. FIG. 5C is a bottom view of tool tip 100. FIG. 5D is a
side view of tool tip 100. As shown in FIGS. 5A-5D, tool tip 100
includes sides 104, tapered and angled front surfaces 106, and a
bottom surface 102 for securing it to surface 98 of tool tip
carrier 90. The front portion 105 of tool tip 100 is used for
machining of a work piece under control of an actuator. Tool tip 90
can be implemented with, for example, a diamond slab.
Interrupted Cut FTS Actuator
An interrupted cut FTS actuator can be used to make small
microstructures as the tool tip is in discontinuous contact with
work piece during cutting, creating non-adjacent microstructures.
These features can be used to make film light guides, micro-fluidic
structures, segmented adhesives, abrasive articles, optical
diffusers, high contrast optical screens, light redirecting films,
anti-reflection structures, light mixing, and decorative films.
The actuator can provide for other advantages. For example, the
features can be made so small as to be invisible to the naked eye.
This type of feature reduces the need for a diffuser sheet to hide
the light extraction features in a liquid crystal display, for
example. Use of crossed BEF films above the light guide also causes
mixing that would in combination with these small features
eliminate the need for the diffuser layer. Another advantage is
that the extraction features can be made linear or circular. In the
linear case, they can be used with conventional cold cathode
fluorescent lamp (CCFL) light sources, for example. In the circular
case, the features can be made on circular arcs with a center point
located where an LED would normally be positioned. Yet another
advantage relates to programming and structure layout where all
features need not lay along a single line as with a continuous
groove. The area density of the light extraction features can be
adjusted deterministically by arranging spacing along the features,
spacing orthogonal to the features, and depth. Furthermore, the
light extraction angle can be made preferential by selecting the
angle and half angles of the cut facets.
The depth of the features may be in the region of 0 to 35 microns,
for example, and more typically 0 to 15 microns. For a roll work
piece, the length of any individual feature is controlled by the
revolutions per minute (RPM) of the rotating work piece along the
c-axis, and the response time of the FTS. The feature length can be
controlled from 1 to 200 microns, for example. For a helix type
cutting, the spacing orthogonal to the grooves (pitch) can also be
programmed from 1 to 1000 microns. As illustrated below, the tool
tip to make the features will taper-in and taper-out of the
material, thereby creating structures, the shape of which are
controlled by the RPM, the response time of the FTS, the resolution
of the spindle encoder, and the clearance angle of the diamond tool
tip (for example, a maximum of 45 degrees). The clearance angle can
include a rake angle of the tool tip. The features can have any
type of three-dimensional shape such as, for example, symmetrical,
asymmetrical, semi-hemispherical, prismatic, and
semi-ellipsoidal.
FIGS. 6A-6H are views of an exemplary actuator 110 for use in
implementing an interrupted cut microreplication system and
process. The term "actuator" refers to any type of actuator or
other device that provides for movement of a tool tip in
substantially an x-direction for use in machining a work piece.
FIG. 6A is a top sectional view of actuator 110. FIG. 6B is a front
sectional view illustrating placement of a PZT stack in actuator
110. FIG. 6C is a front view of actuator 110. FIG. 6D is a back
view of actuator 110. FIG. 6E is a top view of actuator 110. FIGS.
6F and 6G are side views of actuator 110. FIG. 6H is a perspective
view of actuator 110. Some details of actuator 110 in FIGS. 6C-6H
have been removed for clarity.
As shown in FIGS. 6A-6H, actuator 110 includes a main body 112
capable holding an x-direction PZT stack 118. PZT stack 118 is
attached to a tool tip carrier having a tool tip 136 for using in
moving the tool tip in an x-direction as shown by arrow 138. PZT
stack 118 can be implemented with the exemplary PZT stack 72 shown
in FIG. 3. The tool tip on a carrier 136 can be implemented with
the tool tip carrier shown in FIGS. 4A-4D and the tool tip shown in
FIGS. 5A-5D. Main body 112 also includes two apertures 114 and 115
for use in removably mounting it to tool post 36, such as via
bolts, for machining work piece 54 under control of computer
12.
PZT stack 118 is securely mounted in main body 112 for the
stability required for precise controlled movement of tool tip 136.
The diamond on tool tip 136 in this example is an offset 45 degree
diamond with a vertical facet, although other types of diamonds may
be used. For example, the tool tip can be V-shaped (symmetric or
asymmetric), round-nosed, flat, or a curved facet tool. Since the
discontinuous (non-adjacent) features are cut on a diamond turning
machine, they can be linear or circular. Furthermore, since the
features are not continuous, it is not required that they even be
located along a single line or circle. They can be interspersed
with a pseudorandomness.
PZT stack 118 is secured in main body 112 by rails such as rails
120 and 122. The PZT stack 118 can preferably be removed from main
body 112 by sliding is along the rails and can be secured in place
in main body 112 by bolts or other fasteners. PZT stack 118
includes electrical connection 130 for receiving signals from
computer 12. The end cap of PZT stacks 118 includes a port 128 for
receiving cooling fluid such as oil from reservoir 46, circulating
it around the PZT stack, and delivering the oil back to reservoir
46, via port 132, for maintaining temperature control of it. Main
body 112 can include appropriate channels for directing the cooling
fluid around PZT stack 118, and the cooling fluid can be circulated
by a pump or other device in temperature control unit 52.
FIG. 6B is a front sectional view illustrating placement of PZT
stack 118 in main body 112 with the end cap of PZT stack 118 not
shown. Main body 112 can include a plurality of rails in each
aperture for the PZT stacks to hold them securely in place. For
example, PZT stack 118 is surrounded by rails 120, 122, 142, and
144 in order to hold it securely in place when mounted in main body
112. The end cap attached to PZT stack 118 can accommodate bolts or
other fasteners to secure PZT stack to one or more of the rails
120, 122, 142, and 144, and the end cap can also provide for
sealing PZT stack 118 in main body 112 for use in circulating the
cooling fluid around it. PZT stack 118 can include one or more
Belleville washers positioned between the stacks and the tool tip
carrier 136 for preloading of them.
FIGS. 7A-7C illustrate interrupted cut machining of a work piece
using the exemplary actuator and system described above. In
particular, FIGS. 7A-7C illustrate use of variable taper-in and
taper-out angles of a tool tip, and those angles can be controlled
using, for example, the parameters identified above. Each of FIGS.
7A-7C illustrate examples of the work piece before and after being
cut with varying taper-in and taper-out angles. The taper-in angle
is referred to as .lamda..sub.IN and the taper-out angle is
referred to as .lamda..sub.OUT. The terms taper-in angle and
taper-out angle mean, respectively, an angle at which a tool tip
enters a work piece and leaves a work piece during machining. The
taper-in and taper-out angles do not necessarily correspond with
angles of the tool tip as it moves through a work piece; rather,
they refer to the angles at which the tool tip contacts and leaves
the work piece. In FIGS. 7A-7C, the tool tips and work pieces can
be implemented, for example, with the system and components
described above.
FIG. 7A is a diagram illustrating an interrupted cut 150 with
substantially equal taper-in and taper-out angles into and out of a
work piece 153. As shown in FIG. 7A, a taper-in angle 152 of a tool
tip 151 into a work piece 153 is substantially equal to a taper-out
angle 154 (.lamda..sub.IN.apprxeq..lamda..sub.OUT). The duration of
the tool tip 151 into work piece 153 determines a length L (156) of
the resulting microstructure. Using substantially equal taper-in
and taper-out angles results in a substantially symmetrical
microstructure 158 created by removal of material from the work
piece by the tool tip. This process can be repeated to make
additional microstructures, such as microstructure 160, separated
by a distance D (162).
FIG. 7B is a diagram illustrating an interrupted cut with a
taper-in angle less than a taper-out angle into and out of a work
piece 167. As shown in FIG. 7B, a taper-in angle 166 of a tool tip
165 into a work piece 167 is less than a taper-out angle 168
(.lamda..sub.IN<.lamda..sub.OUT). The dwell time of the tool tip
165 in work piece 167 determines a length 170 of the resulting
microstructure. Using a taper-in angle less than a taper-out angle
results in an asymmetrical microstructure, for example
microstructure 172, created by removal of material from the work
piece by the tool tip. This process can be repeated to make
additional microstructures, such as microstructure 174, separated
by a distance 176.
FIG. 7C is a diagram illustrating an interrupted cut with a
taper-in angle greater than a taper-out angle into and out of a
work piece 181. As shown in FIG. 7C, a taper-in angle 180 of a tool
tip 179 into a work piece 181 is greater than a taper-out angle 182
(.lamda..sub.IN>.lamda..sub.OUT). The dwell time of the tool tip
179 in work piece 181 determines a length 184 of the resulting
microstructure. Using a taper-in angle greater than a taper-out
angle results in an asymmetrical microstructure, for example
microstructure 186, created by removal of material from the work
piece by the tool tip. This process can be repeated to make
additional microstructures, such as microstructure 188, separated
by a distance 190.
In FIGS. 7A-7C, the dashed lines for the taper-in and taper-out
angles (152, 154, 166, 168, 180, 182) are intended to conceptually
illustrate examples of angles at which a tool tip enters and leaves
a work piece. While cutting the work piece, the tool tip can move
in any particular type of path, for example a linear path, a curved
path, a path including a combination of linear and curved motions,
or a path defined by a particular function.
FIG. 8 is a diagram conceptually illustrating microstructures that
can be made using the cutting tool system having an interrupted cut
FTS actuator to make a machined work piece and using that work
piece to make a structured film. As shown in FIG. 8, an article 200
includes a top surface 202 and a bottom surface 204. Top surface
202 includes interrupted cut protruding microstructures such as
structures 206, 208, and 210, and those microstructures can be made
using the actuators and system described above to machine a work
piece and then using that work piece to make a film or article
using a coating technique. In this example, each microstructure has
a length L, the sequentially cut microstructures are separated by a
distance D, and adjacent microstructures are separated by a pitch
P. Examples of an implementation of those parameters are provided
above.
While the present invention has been described in connection with
an exemplary embodiment, it will be understood that many
modifications will be readily apparent to those skilled in the art,
and this application is intended to cover any adaptations or
variations thereof. For example, various types of materials for the
tool post, actuator, and tool tip, and configurations of those
components, may be used without departing from the scope of the
invention. This invention should be limited only by the claims and
equivalents thereof.
* * * * *
References